1. Field of the Invention
The present invention relates to an integrated circuit device with a built-in monolithic temperature sensor.
2. Description of the Related Art
Recently, there are growing needs for monitoring the operation temperature of an integrated circuit device for the purpose of preventing thermal breakdown of devices in the integrated circuit device and stabilizing the operation of a device whose characteristic has temperature dependence.
In this respect, Japanese Patent Laid-Open Publication No. H1-302849, for example, discloses a technique of providing a temperature sensor on the same substrate as that of an LSI (Large Scale Integrated circuit). In the technique, the temperature sensor decides that the LSI is abnormally overheated when the temperature detected by the temperature sensor exceeds a predetermined value and then shutting down the LSI. Therefore, it can protect the LSI from thermally broken by a temperature rise. Japanese Patent Laid-Open Publication No. H9-229778 proposes the technique of using a parasitic pn junction diode as such a temperature sensor.
The technique that uses a parasitic pn diode as a temperature sensor has a problem such that as the temperature coefficient of the parasitic pn junction diode is as low as 0.2 (%/K), therefore a sufficient SNR (Signal-to-Noise Ratio) cannot be acquired.
The present inventors have developed a technique of forming a vanadium oxide film as a resistor having an electric resistivity whose temperature coefficient has a large absolute value, and has disclosed it in Japanese Patent Laid-Open Publication No. H11-330051.
The prior art technique suffers the following problems. When a resistor consisting of a vanadium oxide, for example, is formed and the temperature of an integrated circuit device is measured by measuring the resistance of the resistor, the ambient temperature of the resistor may not become uniform due to the influence of the internal and external environments of the integrated circuit device. For example, the flow of the current to wires or the like provided around the resistor locally raises the temperature, thus making the ambient temperature non-uniform. In this case, the internal temperature of the resistor becomes non-uniform, thus making the internal resistivity of the resistor non-uniform, so that the temperature cannot be measured accurately or stably.